ArmPkg/Library/BaseMemoryLibStm/Arm/CopyMem.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # CopyMem() worker for ARM
   4 #
   5 # This file started out as C code that did 64 bit moves if the buffer was
   6 # 32-bit aligned, else it does a byte copy. It also does a byte copy for
   7 # any trailing bytes. It was updated to do 32-byte copies using stm/ldm.
   8 #
   9 # Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
  10 # This program and the accompanying materials
  11 # are licensed and made available under the terms and conditions of the BSD License
  12 # which accompanies this distribution.  The full text of the license may be found at
  13 # http://opensource.org/licenses/bsd-license.php
  14 #
  15 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  16 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  17 #
  18 #------------------------------------------------------------------------------
  19
  20 /**
  21   Copy Length bytes from Source to Destination. Overlap is OK.
  22
  23   This implementation
  24
  25   @param  Destination Target of copy
  26   @param  Source      Place to copy from
  27   @param  Length      Number of bytes to copy
  28
  29   @return Destination
  30
  31
  32 VOID *
  33 EFIAPI
  34 InternalMemCopyMem (
  35   OUT     VOID                      *DestinationBuffer,
  36   IN      CONST VOID                *SourceBuffer,
  37   IN      UINTN                     Length
  38   )
  39 **/
  40 .text
  41 .align 2
  42 GCC_ASM_EXPORT(InternalMemCopyMem)
  43
  44 ASM_PFX(InternalMemCopyMem):
  45         stmfd   sp!, {r4-r11, lr}
  46         tst     r0, #3
  47         mov     r11, r0
  48         mov     r10, r0
  49         mov     ip, r2
  50         mov     lr, r1
  51         movne   r0, #0
  52         bne     L4
  53         tst     r1, #3
  54         movne   r3, #0
  55         moveq   r3, #1
  56         cmp     r2, #31
  57         movls   r0, #0
  58         andhi   r0, r3, #1
  59 L4:
  60         cmp     r11, r1
  61         bcc     L26
  62         bls     L7
  63         rsb     r3, r1, r11
  64         cmp     ip, r3
  65         bcc     L26
  66         cmp     ip, #0
  67         beq     L7
  68         add     r10, r11, ip
  69         add     lr, ip, r1
  70         b       L16
  71 L29:
  72         sub     ip, ip, #8
  73         cmp     ip, #7
  74         ldrd    r2, [lr, #-8]!
  75         movls   r0, #0
  76         cmp     ip, #0
  77         strd    r2, [r10, #-8]!
  78         beq     L7
  79 L16:
  80         cmp     r0, #0
  81         bne     L29
  82         sub     r3, lr, #1
  83         sub     ip, ip, #1
  84         ldrb    r3, [r3, #0]
  85         sub     r2, r10, #1
  86         cmp     ip, #0
  87         sub     r10, r10, #1
  88         sub     lr, lr, #1
  89         strb    r3, [r2, #0]
  90         bne     L16
  91         b   L7
  92 L11:
  93         ldrb    r3, [lr], #1
  94         sub     ip, ip, #1
  95         strb    r3, [r10], #1
  96 L26:
  97         cmp     ip, #0
  98         beq     L7
  99 L30:
 100         cmp     r0, #0
 101         beq     L11
 102         sub     ip, ip, #32
 103         cmp     ip, #31
 104         ldmia   lr!, {r2-r9}
 105         movls   r0, #0
 106         cmp     ip, #0
 107         stmia   r10!, {r2-r9}
 108         bne     L30
 109 L7:
 110   mov   r0, r11
 111         ldmfd   sp!, {r4-r11, pc}
 112